The characteristics of bioaerosol emissions from wastewater treatment plants (WWTPs) have attracted extensive attention. The anaerobic-anoxic-oxic (A²O) process, which uses the activated sludge approach to wastewater treatment, is the most widely used process in WWTPs. Concentration, size distribution, population, and exposure risk from bacteria and fungi in bioaerosols of WWTPs using the A²O process were studied in this work. The results showed that the maximum concentration of airborne bacteria (1.00 × 10⁴ Colony Forming Units per cubic meter (CFU m⁻³)) and fungi (1.44 ×10⁴ CFU m⁻³) occurred from the facility's aerobic tank, in summer. As one of the main factors affecting bioaerosol exposure risk, particle size distribution was related to season. The study found that particles larger than 3.3 µm in diameter were detected mainly in spring and summer, while particles less than 3.3 µm were detected mainly in autumn and winter, whether bacterial aerosol or fungal aerosol. In addition, pathogenic bacteria were observed in bioaerosols from WWTPs, with 18 of the 65 species of bacteria detected found to be potentially or opportunistically pathogenic, such as Chryseobacterium, Stenotrophomonas, Alcaligenes, Micrococcus, Pantoea, Enterobacter and Escherichia-Shigella. The presence of these pathogens further increased the exposure risk from bioaerosols. The results of an inhalation risk assessment for airborne bacteria and fungi indicated that potential adverse health risks for adults mainly occurred in spring, summer, and autumn. On this basis, it was concluded that WWTP operators should set up effective bioaerosol controls as soon as possible to protect the health of workers, and of residents near the plant.

废水处理厂（WWTP）产生的生物气溶胶的排放特征已引起广泛关注。厌氧-缺氧-氧气（A ² O）工艺，采用活性污泥法进行废水处理，是污水处理厂中使用最广泛的工艺。在这项工作中，研究了使用A ² O工艺对污水处理厂生物气溶胶中细菌和真菌的浓度，大小分布，种群和接触风险。结果表明，空气中细菌的最大浓度（每立方米1.00×10 ^4个菌落形成单位（CFU m ^-3））和真菌的最大浓度（1.44×10 ⁴ CFU m ^-3））发生在夏天的设施的有氧水箱中。作为影响生物气溶胶暴露风险的主要因素之一，粒径分布与季节有关。研究发现，直径大于3.3 µm的颗粒主要在春季和夏季被发现，而直径小于3.3 µm的颗粒则主要在秋季和冬季被发现，无论是细菌气溶胶还是真菌气溶胶。另外，在生物气溶胶中观察到从污水处理厂致病细菌，用65种细菌的18检测发现潜在的或机会性致病，如金黄，寡养单胞，产碱杆菌属，微球菌属，泛菌属，肠杆菌属和埃希氏菌属，志贺氏菌。这些病原体的存在进一步增加了生物气溶胶的暴露风险。空气中细菌和真菌的吸入风险评估结果表明，成年人的潜在健康危害主要发生在春季，夏季和秋季。在此基础上得出结论，污水处理厂的经营者应尽快建立有效的生物气溶胶控制措施，以保护工人和工厂附近居民的健康。